What is the likely effect of each of the following mutations of the trpL region on attenuation control of trp operon gene transcription? Explain your reasoning. Twenty nucleotides are inserted into the trpL region immediately after the polypeptide stop codon.

Key Concepts

Attenuation Control

Attenuation control is a regulatory mechanism in prokaryotic gene expression, particularly in the trp operon, where the formation of specific RNA structures determines whether transcription continues or terminates. This process relies on the interaction between the ribosome and the mRNA, allowing the cell to respond to the levels of tryptophan. When tryptophan is abundant, transcription is terminated early, while low levels allow for full transcription.

trp Operon

The trp operon is a cluster of genes in bacteria that encode enzymes necessary for the biosynthesis of the amino acid tryptophan. It is regulated by both repression and attenuation mechanisms, allowing the cell to efficiently manage tryptophan production based on its availability. The operon includes a leader sequence (trpL) that plays a crucial role in the attenuation process.

Mutations and Their Effects

Mutations are changes in the DNA sequence that can affect gene function and regulation. In the context of the trp operon, mutations in the trpL region can alter the formation of RNA structures that are critical for attenuation. For instance, inserting nucleotides can disrupt the normal folding of the mRNA, potentially preventing the formation of the terminator structure and leading to increased transcription of the operon.